article: John lives on a farm. The farm is not very big. His parents grow rice and corn. They don't use animals to do farm work any more. Today they use a tractor . It works faster and better. After he does his work in the fields, he likes to sit and look at the blue sky and the green hills. He thinks the country is more beautiful than the city. In the city, he can't hear the animals. In the country, he can hear birds singing. He likes to play with his dog, Cody. Cody is a very interesting dog. He likes to follow people. When they stop, he stops.
  When they walk, he walks. John thinks Cody is the best dog of all.
question: John's parents are   _  .
options: workers teachers doctors farmers